The present invention relates generally to electronic writing systems. More specifically, the invention relates to techniques for accurately capturing and displaying information on an interactive system, wherein multiple persons may work together for supplying and receiving information with a single large area display.
In a collaborative working environment, several users may wish to view and manipulate displayed information simultaneously. It is desirable to provide a computer controlled electronic large area display system measuring several feet across (both horizontally and vertically.). Each of the multiple users would manipulate an input device which could be used simultaneously and independently for controlling its related pointer on the display in order to position a cursor, select an item from a menu, draw upon the display screen, or perform any number of standard functions. In this way the actions of each user would be readily visible to all the members of the group, who would interact together much as they would relative to a conventional chalkboard or whiteboard.
Computer systems generally incorporate a display unit for providing a visual indication to the user of selected data. A specific location marker, such as a pointer, may be moved by the user to any desired point on the display in order to locate a cursor for the entry of keystroke characters, to trace the locus of points as in drawing alphanumeric characters or other patterns, to invoke and manipulate a functional command such as paint or erase, to open a menu, to invoke a displayed command, or to invoke other interface functions. In each case the location of the pointer must be known, and in many applications the desired control function should be known as well.
Pointer positioning, as a computer input device, has been commonly effected in a variety of ways. For example, by designated keys on a keyboard, by a freely movable "mouse" having one or more function selection buttons thereon, by a "joystick," by means of a stylus upon a graphics input tablet, or by a light pen. Each has its own unique advantages. Keyboard input allows the user to designate a location without removing hands from the keyboard; a mouse is easily and rapidly movable over a pad in correspondence to the display area and its function selection buttons allow various common functions to be invoked; the joystick is also a rapid positioning device; the stylus enables freehand input, and the light pen gives the user additional remote operation in proximity to the display surface.
An imaging system for such a large area writing system may be either projection or non-projection type. A projection-type imaging system desirably should comprise a projection subsystem for projecting the computer display image upon one side of an imaging surface, and a retrieval subsystem for detecting location or function information from the user input device. The image retrieval subsystem should be equally capable of retrieving information from the user's input device when remote from the screen, or when "writing" directly on the screen.
An imaging surface for such a large area writing system should desirably comprise a screen with an imaging surface at or near the front of the screen. The screen should be capable of dispersing light from either a user's light emitting input device or from the projector projecting the computer display image. The screen should be mechanically rigid and durable, and should have a naturally fluid writing "feel." much like a conventional chalkboard or whiteboard, when the user "writes" on it.
A direct input device for such a large area writing system should desirably comprise a wireless light pen emitting optical radiation which could be detected behind the display screen. It should be equally usable, relative to the display screen, as a remote pointer by users comfortably seated several feet from the screen, as well as in "writing" contact with the screen. Being wireless, the pen would have enhanced usability as a collaborative tool since it could be used as a light spot projection device at optimum distances between the screen surface and several feet from it. With wired pens and multiple users, the wires would probably get tangled in this collaborative mode of usage. When the user is writing upon the screen it is preferable to maintain the light pen in contact with the surface being written upon. However, it would be quite practical to project the light spot from several feet away from the screen. The wireless light pen should be capable of pixel location accuracy and should be carefully designed for environmental safety so that, at normal distances of use, its optical beam would be incapable of focusing a light spot on the eye and causing eye damage. The electronic instrumentation controlling the light pen input system is more fully described in copending, coassigned U.S. patent application Ser. No. 07/608,439 of S. A. Elrod et al., entitled "POSITION AND FUNCTION INPUT SYSTEM FOR A LARGE AREA DISPLAY," incorporated herein by reference.